Charge forming device



Jan. 29, 1957 H. MORGENROTH CHARGE FORMING DEVICE 2 Sheets-Sheet 1 FiledJune 9, 1953 INVENTOR. HENRI MORGENROTH Jan. 29, 1957 H. MORGENROTH2,779,576

CHARGE FORMING DEVICE Filed June 9, 1953 2 Shee'ts-Sheet 2 INVENTOR.

HENRI MORGENROTH ATTORNEY United States Patent My invention relates tocarburetors for internal combustion engines and has particular referenceto a combination of reed valve and carburetor wherein the reed valveforms a part of the carburetor structure.

The invention is applicable to internal combustion engines particularlyto two-cycle engines employing crank case compression or the equivalentas when a separate air charging pump is used. Reed valves are thinflexible plate valves which may have one end firmly attached to thevalve seat, while the free portion forms the valve proper, moving anddeflecting as a flap valve when a pressure differential exists. Suchreed valves are used on two-cycle engines where the scavenging andcharging pump is a separate pump as well as on two-cycle engines whereinthe lower side of the working piston forms the pump in conjunction withthe crank case. The invention is applicable to internal combustionengines which are fed by an anterior discharge carburetor. An anteriordischarge carburetor is a carburetor with the fuel or fuel-foamdischarge jet posterior to the air throttle. Such carburetors are usedfor aircraft as well as in some motorcycle carburetor designs.

It' is old and well known to juxtapose the reed valve andthe carburetorfor two-cycle engines, the reed valve being disposed at the dischargeend of the carburetor.

Such structures, however, generally use up a considerable space inasmuchas the barrel or passage through the carburetor is disposed at rightangles to the reed valve, and the entire assembly occupies a veryconsiderable space compared to the total bulk of small two-cycleengines.

It is a general object of the invention to combine an anterior dischargecarburetor with a reed valve.

It is another object of the invention to simplify the construction anddesign of a two-cycle engine carburetor by combining it with a reedvalve.

Still another object is to provide an inexpensive compact and reliablecarburetor for two-cycle engines by combining it with a reed valvestructure.

Other objects and advantages of my invention will be apparent in thefollowing description and claims considered together with theaccompanying drawings in which:

" Fig. l is a longitudinal sectional view through a combined carburetorand reed valve embodying my invention,

Fig. 2 is a view along the line 11-11 of Fig. 1,

Fig. 3 is an outline view of an engine embodying my novel structureshowing the relationship of parts,

Fig, 4 is a sectional view through a modified form of :my combinedcarburetor and reed valve, and

Fig. 5 is a view along the line V-V of Fig. 4.

h Fig. 6 is a view in full section through a modified form of myinvention wherein the throttle valve is a plate valve and the fueldischarges into the airstream as a rich airfuel mixture; and

Fig. 7 is a view along the line VII-VII of Fig. 6.

Referring to Fig. 3 there is illustrated an engine E having a crank caseA to which is secured a carburetor B. A piston P operates within theengine structure and may act as a pump for the air intake to thecrankcase A or a separate charging pump may be used. Fuel may bedisposed in a tank T which may feed a float chamber or bowl D which, inturn, supplies fuel to the carburetor B.

Referring to Figs. 1 and 2 the crankcase A may have side walls 6 uponwhich may be disposed a carburetor body 5 to seal off the inlet openingof the crankcase. The carburetor body may have an air passage 8therethrough which may connect with the interior chamber 1 of thecrankcase A and these two cavities may be intermittently connected by areed valve assembly C. The bottom of the carburetor B may form a valveseat 3 upon which may seat a reed or flexible plate 2 the downwardmovement of which may be limited by an inflexible reed guard 12. Theplate 2 and guard 12 may be secured to the carburetor body 5 by means ofscrews 13. The upper end of passage 8 is the intake end and the lowerend is the discharge end, and this lower end may be formed as a groovein the body 5.

Referring now to the details of the carburetor, the body 5 may haveformed therein two fuel or fuel-foam discharge apertures 10 and 11.Also, the discharge aperture may admit a rich mixture as disclosed in myUnited States Patent 2,638,330 granted May 12, 1953. These dischargeopenings generally speaking may be alternative in their use and both areshown in one figure of the drawings for purposes of illustration and notnecessarily utilitarian design.

The carburetor passage 8 may be controlled by a throttle valve 7 whichmay be of any desired design, for example, the conventional butterflyvalve. Posterior to this throttle valve 7 the passage 8 is shapedparticularly in accordance with my invention and it will be noted from acomparison of both Figs. 1 and 2 that the region designated by thedimension arrow 9 constitutes a restricted area or region with respectto the upstream and downstream portions immediately adjoining it. Thebottom edge of this constricted region 9 is formed by the reed valve 2which normally is seated against the valve face 3. This restricted area9 accordingly is, in fact, a venturi giving rise to the usual lowpressure area in response to air flow at this region so that it issuitable for the use of a fuel jet. It will be noted that the jet 10 ispositioned at this most constricted part so that it may function in theusual fashion of carburetor jets positioned at a venturi.

The alternative fuel jet 11 operates effectively at all speeds. There issuflicient air flow between the valve face 3 and the plate 2 to create alow pressure condition due to the restriction of the air passage as theair escapes around the edges of the plate valve 2. The jet 1]. underthese conditions will then be in a low pressure area akin to a venturiaction and accordingly can function in much the same manner as aconventional fuel jet.

Considering now the operation of the fuel jet 10 the engine E or aseparate charging pump may be started, drawing air through thecarburetor passage 8 under the control of the butterfly 7. On the intakepumping stroke of the piston P (or upon starting a separate pump) theair will flow through the passage 8 unseating the valve 2 and hence flowinto the crankcase passage 1 (or separate pump intake). The region 9being a constricted part of the passage will create a venturi actioncausing fuel or fuel-foam to flow out of the jet 10. The air accordinglywill be carbureted and the crankcase A will be filled with carburetedair mixture ready for use in the combustion chamber of the engine. Whenthe piston P starts its charging and scavenging stroke, pressuredifferential seats the reed valve and the carburetor becomes momentarilyinactive. The throttle valve 7 controls the volume of air flowingthrough the carburetor and hence controls engine speed.

The operation of the alternative fuel jet or aperture arrows v11 issimilar to that for jet 10. This embodiment of the invention used thefuel discharge lll positioned close to the edge of the valve seat 3 onwhich the reed valve 2 comes to rest in its closed position. This is ahigh speed area where consequently suction is existing, While this pointdoes not show the better aerodynamics of a venturi it is neverthelessuseful for this purpose, a pressure drop is created at this point, andconsequently it can be made useful for fuel metering purposes forinterior discharge carburetors. The characteristic of this arrangementis the same as if one wall of an aerodynamically formed venturi isformed by the reed valve, namely, one wall of the restriction is formedby the reed valve. The air at the point of the discharge 11 is speededup and squeezed through a slot-shaped opening formed on one side by thevalve seat 3 and on the other side by the reed valve 2. Theconfiguration of this slot has to be such as to create sufficientsuction for metering purposes. This means that the reed valve preferablyis not too large, or it must not open too far, or a combination of both.Of course, if the valve .seat edge is used as a true venturi throat andthe fuel is metered to the point ll, then other forms of reed valvebodies than those shown in Figs. 1 and 2 can be used. Ordinary reedvalve designs could be used provided their opening area is restricted asexplained before and provided that the air flow is properly directedtowards the reed valve opening so as to create the maximum of suction atthis point.

Illustrated in Figs. 4 and 5 is a modification of my invention whereinthe reed valve constitutes a part of the passage of the carburetor forthe entire length of the passage. Accordingly, there may be secured tothe walls 6 of the crankcase A a carburetor housing 20 having a groove21 formed therein. Secured to the underside of the housing 20 may be areed valve 22 backed up by a reed guard 23. Both may be secured to thehousing 26 in any suitable manner, as by screws 24. The housing 20 maybe secured by suitable means such as screws 26, and a gasket 27 may beinterposed between the housing 20 and the crankcase walls 6. In thisconnection it should be noted that the reed 22 may be extended to theouter face of the housing 20.

The groove 21 and the reed 22 together form a carburetor passagedesignated generally by the numeral 28 and there may be disposed in thispassage 28 an air control valve 29 of any type, for example, a butterflyvalve. A constriction is formed in the groove 21 at the region 31 tothereby form a venturi in the passage 2% A fuel jet 32 may communicatewith the passage at this point. An alternative fuel jet 33 may bedisposed adjacent the most interior end of the passage 28. In Fig. 4 theleft end of passage 28 is the intake end and the right end is thedischarge end.

The operation of the carburetor of Figs. 4 and 5 is similar to that ofFigs. 1 and 2. When the fuel jet 32 is operated the venturi action inthe region 31 causes a metering of fuel from the jet 32. When it isdesired to use the metering action of the air flow between the groove 28and the reed valve 22, then the jet 33 may be used. The air valve 2? maybe used to control total air flow and hence power output of the engine.

As used in this specification the word jet is synonomous with fueldischarge opening or aperture. The word jet is used in its sense as anozzle or outlet opening and not in the sense of a controlled flow ormetered device.

Referring to Figs. 6 and 7 there is illustrated a carburetor body 43secured to the crankcase A by suitable means such as bolts or screws 41.The body 4 may have an air passage 42 therein which is intermittentlycommunicated with the crankcase by a reed 43 backed by a guard 44 andboth secured by suitable means such as a fastener 46. The conduit formedby the walls of the passage or groove 42 and the reed valve 43 may havea region of maximum constriction as at 47 wherein a .venout is formed. Afuel discharge opening 48 may com- 4 municate with the air passage 42 athis region 47 and .a smaller fuel discharge opening 49 may communicatealso with passage 42 downstream or posterior to passage 48.

Disposed on the top of body 40 may be a valve plate 51 mounted forsliding pivotal action in a thin space 52 formed between the body 40 anda cap 53. The valve plate 51 may be secured to a shaft 54 journaled forrotation in the cap 53, permitting the valve plate to swing from oneextreme to the other in space 52 (Fig. 7). Formed in cap 53 may beapertures or passages 42a, 45in and 49a registering with the passages42, 48 and 49 respectively. The valve plate may have a close fit in itsspace 52 to limit leakage between the passages 42a, 48a and 49a.

The passage 48a may have a venturi formed therein at which point a fueldischarge opening 56 may be provided supplied by a conduit 57. Thepassage 49a may be constricted by a screw 58 and a fuel conduit 59 maydischarge into this passage posterior to the screw. The passages aha and49a act as rich mixture carburetors and the resultant rich mixture ismetered by the air passage venturi 47. The air flow through these richmixture carburetors may be carefully regulated and tailored by means ofspecially configurated apertures 42b, 48b and 49b formed therein, givingrise to variant flow and control according to any preselected pattern.The rich mixture carburetor of passage 49a is especially effective atlow and idle speeds.

The operation of the charge forming device of Figs. 6 and 7 is that therich mixture is diluted at the venturi 47 to form a desired air-fuelmixture when the reed valve 43 is open. When the reed valve is closedthe charge forming device is ineffective.

l have discovered that passage friction gives rise to an apparentconstriction which causes a low pressure area. This low pressure varieswith the volume of air flow and can be used as a metering device in thesame manner as a venturi especially with highly sensitive fuel feedingmechanism, for example, the rich mixture carburetor disclosed in my saidPatent 2,638,330. Such friction takes place in a plain passage wherein areed forms part of the passage.

It can be seen from the drawings that the venturi is arranged in such away as to be substantially parallel to the reed valve. This arrangementserves two functions. First it gives a very nicely streamlined flow,which does not force as sharp bends in the air or mixture stream asusually found in induction systems with the carburetor discharging in avertical axis towards the reed valve. The second purpose is to eliminatea separate casting for the reed valve seat thus saving both onmanufacturing cost and the size of the combined apparatus. It can be.seen that one wall of the venturi throat is formed by the reed valveproper. The slight amount of opening at the carburetor throat of courseincreases the size of the throatsomewhat, but this opening being alwaysthe same, it is easy to compensate for it by proper selection of thefuel meters orifice. Another a n g f thi fo mat on of on wall of theventuri by the reed valve is in manufacture with the die casting method.Here an -accurately formed venturi throat can easily be cast without theuse ,of slides or without the need for further machining.

With regard to Figs. 1 and 2 it is not necessary that fuel outlet 11 bepositioned at the point of greatest deflection of the valve reed 2. Allthat is required to obtain a ven ri-like met ring act on i a c nsriction in the air stream. The reed valve 2 constricts the air all aboutits entire end. A metering action occurs therefore in a U- shaped regionaround the entire end of the reed 2 as viewed in Fig. 2. It would bepractical therefore to place the fuel outlet at any point outwardly fromabout the region 9.

Frequently a number of reed valves are u ed to control th inductionsystem of two cycle engines- These may be arranged separately orcombined as for instance in the form of a star. The invention asillustrated in Figs. 1 and 2 can also be used in conjunction with suchmultiple finger reed valves. It is merely necessary to form at least oneof these reed valves according to the before given description while theothers can maintain their conven tional form and shape.

It is to be understood that other forms of execution are possible aswould be apparent to persons skilled in the art.

I claim:

1. A carburetor comprising: a housing having a passage formed thereinwith an intake end and a discharge end, at least the discharge end ofwhich is an open groove; a venturi constriction formed in the opengroove creating part of a venturi whereat the groove cross sectionalarea is less than the groove portions immediately posterior andanterior; a reed valve positioned over the discharge end of said grooveand opposite said groove constriction to form part of and to completethe venturi and to form part of the passage walls at, and to normallyclose ofi, the groove portion of said passage; a fuel discharge aperturein said housing at a low pressure area in said passage created by saidventuri; and an air valve in said passage anterior to said fueldischarge aperture.

2. A carburetor comprising: a housing having a passage formed thereinwith an intake end and a discharge end, at least the discharge end ofwhich is an open groove; a venturi constriction formed in the opengroove dis charge end of said passage to form part of a venturi andhaving a lesser cross sectional groove area than the groove portionsimmediately anterior and posterior to the venturi to create a first areaof constriction; a reed valve positioned over the discharge end of saidgroove and opposite the venturi constriction to form part of the passagewalls and to complete the venturi at the first area of constriction, andsaid reed valve having its greatest deflection at the extreme dischargeend of said passage whereby a second area of constriction is createdwhen said reed val e is open; a fuel discharge opening communicatingwith the passage in at least one of said areas of constriction; and onair valve for said passage anterior to both of said areas ofconstriction.

3. A carburetor as defined in claim 2 wherein a fuel opening is locatedat each area of constriction.

4. A carburetor as defined in claim 2 wherein a fuel opening is locatedat the first area of constriction.

5. A carburetor as defined in claim 2 wherein a fuel discharge openingis located at the second area of constriction.

6. A carburetor as defined in claim 2 wherein the entire intake end ofthe passage is defined by said housing.

7. A carburetor as defined in claim 2 wherein the entire passage is anopen groove and the reed valve completes the passage.

References Cited in the file of this patent UNITED STATES PATENTS1,307,665 Guider June 24, 1919 2,442,217 Smith May 25, 1948 2,459,594Smith Jan. 18, 1949

